The U.S. Patent and Trademark Office's (USPTO) Central Reexamination Office (CRO) has damaged Apple, Inc.'s (AAPL) legal campaign against rival smartphone maker Samsung Electronics Comp., Ltd. (KSC:005930) with its third in a series of major patent rejections in recent months.

On Wednesday, the CRO ruled [PDF] that Apple's "pinch to zoom" patent -- U.S. Patent No. 7,844,915 -- was invalid [PDF]. The patent claims the invention of a number of things multi-touch related -- including being able to distinguish between single finger scrolling gestures and a plurality of multi-finger gestures, including the aforementioned pinch to zoom.

These multi-touch techniques were largely first demonstrated in the 1980s in the world of academia by groups such as Myron Krueger's team at the University of Toronto. Professor Krueger developed and published papers on virtually equivalent pinch-to-zoom multi-touch technology almost 25 years prior to Apple producing its first multi-touch device (the iPhone).

How critical would it be if these three Apple patents were invalidated? The invalidation would eliminate two out of the three utility patents that Apple asserted in winning a $1.05B USD verdict against Samsung. As a result the invalidations could slash hundreds of millions of dollars off the damages verdict.

One advantage Apple does have in both the '915 and '381 invalidations is that they are ex parte evaluations; meaning that Apple is the only party the USPTO is discussing the matter with. Thus it's possible Apple could rectify the language in the patent to be less ambiguous, but in such a way to try to preserve its trial verdict against Samsung.

Also, it should be noted that while all of the patent's 21 claims were rejected, only a single claim -- Claim 8 -- was used in the Samsung case.